Double-Molded Electric Unit Encasement for Moisture Sealing Accuracy
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Solution Overview
Problem
Existing methods for encasing electrical units, such as sensors, face issues with moisture diffusion leading to corrosion and short circuits, inability to meet customer-specific installation space requirements, and challenges in achieving high tightness classes, along with thermal expansion-related measurement inaccuracies.
Innovation Solution
A method involving connecting the electrical unit to a leadframe, encasing it with a first plastic material to form an inner mold body, and then surrounding it with a second plastic material in a cage structure, decoupling the outer mold body from the inner to prevent distortion and thermal stresses, while ensuring chemical and mechanical stability and easy integration of a shielding plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the circuit board is located in a cavity with full encasement, then protection against moisture and corrosion is improved, but thermal expansion stresses distort measurements
Solution Approach 1:
The housing is divided into two separate plastic bodies (first and second plastic bodies) that partially enclose the circuit board rather than forming a single complete cavity. This segmentation prevents full encasement while maintaining protection, allowing the circuit board to remain exposed to some extent and avoid thermal expansion stresses that would distort measurements.
2Reliability
If a complete housing encloses the circuit board, then sealing class is improved, but design and manufacturing complexity increases
Solution Approach 1:
The housing is segmented into two separate plastic bodies that are manufactured independently and then assembled together. This reduces the complexity of manufacturing a single complete housing while still achieving the required sealing class through the combined structure of both bodies.
Solution Approach 2:
The first plastic body is partially enclosed by the second plastic body, creating a nested structure where one housing component is placed within another. This nested design allows for simplified manufacturing of individual components while achieving high sealing performance through their combined configuration.
3Adaptability or versatility
If different plastic materials are used for housing bodies, then adaptability to different sensors is improved, but thermal expansion differences cause distortion
Solution Approach 1:
The housing is divided into two separate plastic bodies that can be made from different plastic materials. By segmenting the housing, the patent allows each body to be optimized for different sensors while the partial enclosure design prevents thermal expansion stresses from directly affecting the circuit board and causing measurement distortion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach prevents corrosion, migration, and short circuits, reduces design and qualification efforts, and enhances measurement accuracy by decoupling thermomechanical forces, allowing for effective shielding and cost-effective production of assemblies with high mechanical and chemical resistance.
Implementation Method 1
encasing the electrical unit with a first plastic material to form an inner molded body
Implementation Method 2
forming an outer molded body surrounding the inner molded body from a second plastic material at least partially in the form of a cage structure
Implementation Method 3
the outer molded body only partially rests against the inner molded body and is partially spaced from the inner molded body... protectors can be formed against static and dynamic forces... Thermomechanical forces, for example, from a thermoplastic on a thermoset and from there to a sensor element, are largely prevented
Data Source
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AI summary
The invention relates to a method for covering an electric unit, said electric unit being connected to a lead frame and being covered twice. The invention also relates to an associated electric component.